<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<script>
	     
	    num1 = prompt("请输入你要运算第1个值");
	    yunsuan = prompt("输入你要做的运算");
		num2 = prompt("请输入你要运算第2个值");

		// document.write(num1,yunsuan,num2);

		switch(yunsuan){
			case "+": 
				document.write(Number(num1)+Number(num2))
			break;
			case "-": 
				document.write(Number(num1)-Number(num2))
			break;
			case "*": 
				document.write(Number(num1)*Number(num2))
			break;
			case "/": 
				document.write(Number(num1)/Number(num2))
			break;
			default:
				document.write("无法自动，请正确输入");
		}



		num = 100;

		if(num>90){
			1
		}else if(num>95){
			2
		}else{
			3
		}


		if(num>90){
			1
		}
	
		if(num>95){
			2
		}


	</script>
</head>
<body>
	
</body>
</html>